反应详情

Malonic acid (44 g, 0.42 mol), 2-methylpentan-1-al (14 g, 0.14 mol) and piperidine (1.7 ml) were suspended in 85 ml pyridine and heated under reflux. Gas formation was observed which ceased after two hours. Heating was continued for 1 hour. The cooled reaction mixture was poured into 2M hydrochloric acid (200 ml) after which two phases were obtained which were separated in a separating funnel. The aqueous phase was extracted once with dichloromethane (60 ml). The organic phases were combined and the solvent removed under reduced pressure. The residue was purified by column chromatography (pre-packed silica column, gradient of pentane/ethyl acetate). 9.3 g (0.065 mol, 47% yield) of (E)-4-methyl-hept-2-enoic acid were obtained as a solid. NMR (1H, CDCl3, 300 MHz): 11.86 (s, 1H), 7.00 (dd, 1H), 5.79 (d, 1H), 2.35 (m, 1H), 1.35 (m, 4H), 1.06 (d, 3H), 0.89 (m, 3H).

1. temperatureheated
2. temperatureunder reflux
3. temperatureHeating
4. waitwas continued for 1 hour
5. customThe cooled reaction mixture
6. customwere obtained which
7. customwere separated in a separating funnel
8. extractionThe aqueous phase was extracted once with dichloromethane (60 ml)
9. customthe solvent removed under reduced pressure
10. customThe residue was purified by column chromatography (pre-packed silica column, gradient of pentane/ethyl acetate)